Image navigation technology has been developed to indicate and track the relative position of various body parts and surgical instrumentation and implants during medical and surgical procedures. Image navigation systems typically utilize scans obtained either prior to or during a medical or surgical procedure to generate two-dimensional or three-dimensional images of various parts of the body. Such images aid the surgeon in manipulating and guiding surgical instruments, equipment and/or implants during various medical or surgical procedures. Interest in image navigation technology has increased as a result of recent advances in scanning technology, particularly with regard to technological advancements in devices that use computers to generate three-dimensional images, such as computed tomography (CT) or magnetic resonance imaging (MRI).
In the past, use of image navigation technology has been primarily directed to applications involving image guidance systems relating to the cranium. In such applications, the skull provides a convenient reference point for rigid attachment of an image navigation reference device, such as, for example, a surgical navigation reference frame. Recently, image navigation technology has been applied to other areas of the body including the spinal column. Surgical procedures involving the spinal column may be used, for example, to stabilize and/or fuse portions of the spine or to correct various spinal deformities or degenerative conditions. A number of surgical navigation systems have been developed for specific application to surgical procedures involving the spinal column. U.S. Pat. No. 6,226,548 to Foley et al. discloses one such system. A similar system is disclosed in U.S. Pat. No. 6,236,875 to Bucholz et al.
As illustrated in FIG. 1, surgical procedures involving the spine typically require the formation of a relatively large surgical incision I through the skin S of the patient adjacent the portion of the spinal column to be treated, usually extending along two or more levels of vertebrae V. The size of the surgical incision I must be large enough to accommodate for the manipulation and/or placement of various surgical instruments and implants required for the surgical procedure. Additionally, if image navigation technology is to be used in association with the surgical procedure, the surgical incision I must also accommodate for the mounting of a reference frame or registration device to the spinal column.
As illustrated in FIG. 2, the size of the surgical incision I must be large enough to permit anchoring of an image navigation reference frame or registration device 20 to at least one of the vertebrae VA. The reference frame 20 is typically anchored to the vertebra VA via a bone clamp 22 having at least two opposing blades or jaws 24 which include inwardly-facing pointed tips or teeth 26 that provide secure engagement with vertebral bone. The blades 24 are typically clamped about the spinous process 28 of the vertebra VA to maintain the reference frame 20 in a substantially fixed position relative to the vertebra VA. The blades 24 are sized to receive the bulb-shaped portion of the spinous process 28 therebetween and the teeth 26 are configured to penetrate into bone tissue for secure fixation thereto. However, if teeth 26 are used to secure the clamp 22 to the vertebra VA, care must be taken to avoid damage or trauma to the vertebral bone. This is of particular concern when dealing with patient's having soft bone material, such as might be found in older patients or patients afflicted with a bone weakening disease (e.g., osteoporosis). Alternatively, one or more fasteners (not shown) may be used to anchor the reference frame 20 to the vertebra VA via insertion into the spinous process 28. However, the use of fasteners to anchor the reference frame 20 to the vertebra VA requires precise placement to avoid damage to adjacent neural structures, blood vessels and delicate tissue. Moreover, the use of fasteners may result in increased trauma to the vertebra VA. A fiducial array 30 may also be anchored to the vertebra VA via the bone clamp 22. The fiducial array 30 provides feedback to the surgical navigation system regarding the precise location of the vertebra VA by touching a pointed surgical tracker (not shown) against various reference points along the fiducial array 30.
As also illustrated in FIG. 2, mounting of the reference frame 20 directly to the patient's spinal column creates a structural obstruction directly above and around the surgical site that could potentially interfere with or hinder the surgeon during the surgical procedure. Notably, mounting the reference frame 20 to the patient's spinal column must be done in an intra-procedural setting, subsequent to formation of the surgical incision I and commencement of surgery, thereby tending to increase the overall length of the surgical procedure. Moreover, after forming the surgical incision I, the surgeon must stand by and wait while other medical personnel acquire radiographic images of the patient's spinal column. The relatively lengthy wait encountered by the surgeon during this surgical procedure results in inefficient use of the surgeon's time. Additionally, since acquisition of the radiographic images must be done in an intra-operative setting, there is a higher risk of potential infection because the incision must be open for a relatively lengthy period of time.
As discussed above, the use of image navigation systems in surgical procedures involving the spinal column typically requires the formation of a relatively large surgical incision. Large surgical incisions are highly invasive and can result in increased trauma, blood loss, post-operative pain, and a lengthy recovery period. It would therefore be desirable to provide instrumentation and methods for the mounting of an image navigation reference frame to the patient in a minimally invasive manner to reduce the size of the surgical incision, or by eliminating the surgical incision entirely in applications involving fluoroscopic surgery or percutaneous surgical procedures. It would also be desirable to mount the image navigation reference frame to the patient at a location remote from the surgical site to eliminate structural obstructions above and proximately adjacent the surgical site, thereby providing the surgeon with a relatively unobstructed area to perform the surgical procedure. Moreover, it would be desirable to mount the image navigation reference frame to the patient in a pre-procedural setting at a time prior to formation of the surgical incision and commencement of surgery, thereby reducing the overall length of the surgical procedure and the risks associated therewith. Mounting the reference frame to the patient in a pre-procedural setting would also allow the acquisition of radiographic images without the hindrance of surgical drapes.
Thus, there is a general need to provide improved instrumentation and methods for performing image-guided spinal surgery than is currently available within the industry. The present invention meets this need and provides other benefits and advantages in a novel and unobvious manner.